The Effect of Hypothyroidism on Color Contrast Sensitivity: A Prospective Study

Background: Thyroid hormone has been shown to control retinal cone opsin expression, the protein of color vision, in adult rodents. Objectives: The aim of this study was to evaluate the effect of hypothyroidism on color contrast sensitivity in adult overt hypothyroid patients. Methods: Thirtyeight overt hypothyroid (31 females, 7 males) subjects and 20 euthyroid (16 females, 4 males) controls were studied prospectively. Color vision examination was performed by Chromatest, a software program analyzing the tritan (blueyellow) color contrast threshold (tritan CCT) and protan (redgreen) color contrast threshold (protan CCT). Color contrast sensitivity analyses of hypothyroid subjects were performed on admission and after L -thyroxine treatment when biochemical euthyroidism was achieved. Results: After a median period of 90 (90–210) days, 24 (19 females, 5 males) patients were euthyroid and eligible for a second color vision examination. Baseline tritan CCT and protan CCT values were significantly higher in the hypothyroid group compared to euthyroid controls, which clinically translates into impaired color contrast sensitivity (p < 0.001 and p < 0.001, respectively). There was a significant decrease in tritan CCT (p = 0.002) and protan CCT (p < 0.001) values in the hypothyroid Received: September 12, 2014 Accepted after revision: December 15, 2014 Published online: February 7, 2015 Mehtap Cakir, MD Konya Necmettin Erbakan University Division of Endocrinology and Metabolism TR–42080 Konya (Turkey) E-Mail cakirmehtap @ yahoo.com © 2015 European Thyroid Association Published by S. Karger AG, Basel 2235–0640/15/0041–0043$39.50/0 www.karger.com/etj This study was presented as an oral presentation (No. OP19) at the 36th European Thyroid Association Meeting, September 2012, Pisa, Italy. D ow nl oa de d by : 54 .7 0. 40 .1 1 11 /2 0/ 20 17 2 :5 0: 16 A M